Environmental concerns and governmental regulations require reduced emissions of volatile hydrocarbon fuel vapors into the atmosphere. One source of hydrocarbon fuel vapors is fuel tanks of vehicles using gasoline or other high volatility hydrocarbon fuels. Fuel vapor can escape to the atmosphere during filling of fuel tanks and even after the tanks are filled. The use of vapor recovery systems to remove excess fuel vapor from the fuel tank is one solution that is commonly used to abate the problem. Such systems may include, a canister having activated charcoal therein which receives fuel vapors through a valve assembly mounted in the top of the fuel tank and communicates with the intake manifold of the vehicle engine for withdrawing fuel vapor from the canister during operation of the engine. The valve assembly may have a valve responsive to the level of fuel in the tank that enables the valve to stay open when there is a low fuel level to permit fuel vapors to flow from the fuel tank into the canister. As the level of fuel rises during a refueling operation, a float is raised to close the valve to prevent liquid fuel from flowing through the valve and into the vapor recovery system.
Governmental regulations also mandate that a vapor control valve remain closed during a vehicle rollover, such that fuel does not escape from the fuel tank and pose a hazard.
Therefore, there is a need in the art for a vent valve that complies with the environmental concerns and governmental regulations, is of a simple design that does not require complex interactions among components, cost-effective, and in service has a long useful life.